Appliance for cooking food, in particular fryer, comprising a catalyst and means for regulating said catalyst

ABSTRACT

An appliance for cooking food in a closed atmosphere, the appliance including a bowl ( 6 ) and a lid, heater means for heating the appliance, for the purpose of performing the cooking, and a catalytic converter ( 10 ) for treating the odors of the cooking fumes before the fumes are discharged to the outside, wherein, the catalytic converter ( 10 ) includes at least one heater element, and the appliance further comprises temperature regulation means ( 12 ) for regulating the temperature of said heater elements, the temperature regulation means ( 12 ) being organized to sense the temperature of the cooking zone.

TECHNICAL FIELD

[0001] The present invention relates to the general field offood-cooking appliances of the deep-fryer type equipped with means fortreating cooking odors, which means comprise a catalytic subassemblythrough which cooking fumes or vapors pass before they are discharged tothe outside of the appliance.

[0002] The present invention relates to an appliance for cooking food ina closed atmosphere, the appliance being of the deep fryer type forexample, and comprising a bowl and a lid, heater means for heating theappliance, be they internal or external to the appliance, for performingcooking proper, and a catalytic converter for treating the odors fromthe cooking fumes or vapors before said cooking fumes are discharged tothe outside of the appliance.

PRIOR ART

[0003] When cooking food, be it by steaming in rice cookers, forexample, or by cooking in oil in deep-fryers, it is observed thatcooking fumes are emitted to various extents depending on the type ofcooking and on the cooking fluid used, such emitted fumes having acharacteristic odor that is generally disliked by the user, and that itis desirable to prevent or to treat.

[0004] One of the first known treatment means naturally consists incooking the food in a closed atmosphere by implementing a suitablyleaktight connection between the bowl and the lid of the appliance.

[0005] However, for obvious safety reasons, in particular in pressurecookers or in deep fryers, it is always necessary to provide a leakageoutlet for the cooking fumes, and that is why such appliances areequipped with means for treating cooking odors in order to rid thecooking fumes of all or some of the volatile molecules responsible forthe cooking odor.

[0006] Various devices have been devised, and in particular it is knownthat activated carbon filters can be used that make it possible toretain all or some of the grease, as is described, for example, inPatent FR-1 568 985 or in Patent EP-150 516.

[0007] Unfortunately, in order to be effective, activated carbon filtersin the cooking appliance must be changed frequently, which constitutesan additional design constraint for the appliance insofar as it isessential to make provision to design a system for fitting and removingthe activated carbon filter. In addition, it is observed that the userfrequently forgets to change the activated carbon filter, such anoperation being perceived as a chore. The combination of all of thosereasons makes the use of activated carbon filters ill-suited fortreating cooking odors. In addition, they are not absolutely anduniversally effective and they also allow the stream of treated fumesdischarged from the appliance to be seen.

[0008] A system for treating frying odors is also known that consists incondensing the cooking fumes in a condensation system mounted in theappliance. Such a system does not suffer from the drawbacks of having tochange all or some of the system as is required for activated carbonfilters, but it does require the user to perform a relatively tediousaction each time a cooking operation is effected. The condensationsystem must be kept at a very low temperature, e.g. in a freezer,throughout the periods during which it is not in use, and it must thenbe fitted to the cooking appliance itself before any cooking operation.In addition, that system must then be emptied after the cookingoperation. The requirement to make the system cold again preventsanother cooking operation from being performed with the same system for24 hours. This systematic fitting operation can be perceived by the useras an additional chore. Furthermore, condensation systems are generallylarge in volume, which constitutes a further design constraint insofaras it is necessary to integrate such a system into a cooking appliancewhose size must generally be limited.

[0009] Finally it is already known that catalytic converters can be usedfor the purpose of treating cooking odors in particular when fitted todeep fryers. The use of catalytic converters avoids any specific actionbeing necessary, unlike systems including activated carbon filters orcondensation systems, because the catalytic converter is installedpermanently in the appliance, and thus forms a permanent odor treatmentunit.

[0010] Unfortunately, the use of a catalytic converter in a food-cookingappliance, and in particular in a deep fryer, is difficult to implementinsofar as the temperatures reached can be high and can be dangerous forthe structural integrity of the appliance and for the user. In addition,in order to obtain good treatment of the cooking odors, and in order tomake the treated and discharged cooking fumes invisible, it is necessaryto reach temperatures that are sufficiently high. At the same time, itis not possible, for safety reasons, to prefer operating a catalyticconverter at temperatures that are too low because the efficiency of thecatalytic converter is then too low, and it is then observed thatresidual cooking odors remain.

[0011] It can thus be understood that integrating catalytic convertersinto food-cooking appliances, and in particular into deep fryers, is anoperation that is difficult to implement, and that it is desirable todesign food-cooking appliances that are provided with catalyticconverters but that are nevertheless capable of operating under goodconditions.

SUMMARY OF THE INVENTION

[0012] An object assigned to the invention is thus to remedy the variousabove-mentioned drawbacks of the prior art, and to provide a novelappliance for cooking food in a closed atmosphere, which appliance isequipped with a catalytic converter for treating the cooking odors, andis capable of operating well by using means that are simple, safe, andeffective.

[0013] Another object of the invention is to provide a novel cookingappliance in which operation of the catalytic converter is regulated bymeans that are simple and reliable.

[0014] Another object of the invention is to provide a novel cookingappliance whose manufacturing cost is particularly low.

[0015] Another object of the invention is to provide a novel cookingappliance in which the efficiency of the catalytic converter isparticularly high and obtained by means that are simple are inexpensive.

[0016] Another object of the invention is to provide a novelfood-cooking appliance in which the efficiency of the catalyticconverter is particularly high, and in which discharge of the fumes isinvisible.

[0017] An additional object of the invention is to provide a novelcooking appliance whose operating safety is reinforced.

[0018] The objects assigned to the invention are achieved by means of anappliance for cooking food in a closed atmosphere, the appliancecomprising a bowl and a lid, internal or external heater means forheating the appliance, for the purpose of performing the cooking, and acatalytic converter for treating the odors of the cooking fumes beforesaid fumes are discharged to the outside, said appliance beingcharacterized in that:

[0019] the catalytic converter includes at least one heater element; and

[0020] the appliance further comprises temperature regulation means forregulating the temperature of said heater elements, said means beingorganized to sense the temperature of the cooking zone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other objects and advantages of the present invention will appearin more detail on reading the following description with reference tothe accompanying drawings which are given by way of non-limiting andillustrative example, and in which:

[0022]FIG. 1 is an overall perspective view of a food-cooking applianceof the invention (a deep fryer in this example);

[0023]FIG. 2 is a fragmentary perspective view showing a detail of anembodiment of the inner portion of a deep fryer of the invention; and

[0024]FIG. 3 is a fragmentary section view on a transverse plane,showing a detail of an embodiment of a catalytic converter of theinvention, as fitted in the removable lid of a deep fryer.

BEST MANNER OF IMPLEMENTING THE INVENTION

[0025] In the embodiments shown in FIGS. 1 to 3, the food-cookingappliance of the invention that is described is constituted by a deepfryer serving for and designed for deep frying all kinds of food in fat,such as a bath of oil, for example. For the purposes of the invention,the term “food-cooking appliance” should nevertheless be extended tocover all domestic food-cooking appliances that are suitable for cookingfood, application to frying appliances of the deep fryer type beingmerely a preferred application, it naturally being possible for theinvention to be applied to other uses such as to rice cookers or tomulti-purpose cookers, provided that such cooking appliances implementcooking in a cooking fluid contained in a closed enclosure that issubstantially leaktight.

[0026] The food-cooking appliance shown in FIGS. 1 to 3, which is anelectric deep fryer in this example, comprises a base 1 serving to formthe stand for the appliance and designed to rest on a support surface orworktop. The base 1 is generally integral with an outer skirt 2 or elseit is separate and secured thereto, the skirt being made, for example,of a metal or of a heat-resistant plastic forming the outer casing ofthe deep fryer. However, the outer skirt 2 is conventionally made of aplastic that is cheap and not very heat-resistant such as polypropylene,and that cannot withstand the heat energy dissipated continuously by thehigh-temperature heater elements conventionally used in electric deepfryers, and generally disposed at the bottom in the vicinity of the base1.

[0027] The heater means of the appliance (not shown in the figures) maybe internal to the appliance and conventionally composed of metal-cladelements or equivalent elements, connected, also conventionally, to anelectrical connection unit (not shown) and to electrical cabling makingit possible to connect the appliance to the mains. Also in a mannerknown to the person skilled in the art, the cooking appliance of theinvention is provided with a set of electrical or electronic safetymeans such as temperature sensors, fuses, etc. required when designingsuch appliances. Since these elements are well known to the personskilled in the art, they are not described in any more detail in theremainder of the description. The heater means may also be external tothe appliance and separate or separable therefrom.

[0028] The outer skirt 2 may be of any suitable and attractive shape,e.g. circular, oval, or rectangular, so as to define, for example, sidefaces 3 and front and back faces 4.

[0029] The top portion of the outer skirt 2 is advantageously providedwith an annular ring for mechanically coupling the top portion of theouter skirt 2 to a cooking bowl 6 which is generally made of metal andwhich serves to receive the frying oil and the food to be fried.Advantageously, and as is well known to the person skilled in the art,and as described, for example, in Patent FR-87 06728, the annular ringis advantageously made of a thermally insulating material thatcontinuously withstands the operating temperatures of the deep fryer,e.g. polyamide, polyester, polybutylene terephthalate (PBTP) or thelike, and said ring supports the cooking bowl 6, at least in part.

[0030] For the purposes of the invention, the base 1, the outer skirt 2,and the annular ring together form the main body of the food-cookingappliance of the invention.

[0031] In the invention, the deep fryer has a removably mounted lid 7hinged relative to the main body of the deep fryer and serving, duringthe cooking, to close said main body in substantially leaktight manner,e.g. by means of sealing gaskets (not shown in the figures).

[0032] Advantageously, and as shown in FIGS. 1 and 2 in particular, thelid 7 may be provided on its top face 8 with an inspection window 9making it possible to monitor the progress of the cooking or of thefrying throughout the cooking cycle, and while the lid is closed on themain body.

[0033] Cooking food in a closed environment in a cooking fluid, be it bysteaming or by frying, generates characteristic and often unpleasantodors resulting from chemical reactions related to the cooking proper,and in particular to the emission of volatile organic compounds.

[0034] The appliance for cooking food in a closed atmosphere thuscomprises a bowl 6, a lid 8, and heater means that are internal orexternal and that serve to perform the cooking. It further comprises asystem for applying heat treatment to the cooking odors, namely acatalytic converter 10 for treating the odors from the fumes before theyare discharged to the outside of the appliance.

[0035] In the invention, and as illustrated, for example, in FIG. 3, thecatalytic subassembly 10 includes at least one heater element 11, theappliance further comprising regulation means 12 for regulating thetemperature of said heater elements 11, said regulation means 12 beingorganized to sense the temperature of the cooking zone.

[0036] By means of this configuration, it is thus possible to regulatethe temperature of the heater elements 11 of the catalytic converter 10via a thermal image that is not situated in the catalytic converteritself but rather that corresponds to an image representative of thetemperature prevailing in the cooking fluid.

[0037] In the invention, the temperature regulation means 12 comprise atemperature sensor 12A mounted in a manner such as to sense thetemperature of the cooking bowl 6 as an image of the cookingtemperature.

[0038] Advantageously, and as shown in FIG. 2, the temperature sensor12A is mounted against or on the outer wall of the bowl 6. Thetemperature sensor 12A may also be mounted against or on the inside wallof the bowl 6, and then be in the cooking bath itself. It is thusagainst or on the side wall of the bowl 6.

[0039] In a manner well known to the person skilled in the art, thetemperature sensor 12A may be a thermostat (FIG. 2), a bimetallic strip,or any other equivalent means such as a bulb or a shape memory alloy(SMA), for example.

[0040] Advantageously, and as shown in FIG. 2, the temperature sensor12A is mounted on the bowl 6 at a height corresponding to the height ofthe bath of oil and, for example, half way to the maximum permittedheight for the bath of oil. By way of a variant, the temperature sensor12A may also be mounted against or on the bottom of the bowl 6.

[0041] As is well known to the person skilled in the art, the applianceof the invention further comprises a temperature regulation system (notshown) for regulating the temperature of the heater means, and, forexample, including a thermostat, said system serving for regulating thetemperature of the appliance and of the oil bath as a function of thereference temperature set by the user.

[0042] In a particularly advantageous version of the invention, thetemperature regulation system for regulating the temperature of theappliance heater means is associated with the temperature regulationmeans 12 for regulating the temperature of the catalytic converter 10,said regulation system including a temperature sensor common to thetemperature regulation means 12. In this variant, the temperature sensor12A serving for regulating the temperature of the heater elements 11 ofthe catalytic converter, thus also serves for regulating the temperatureof the heater means of the deep fryer. The temperature of the catalyticconverter 10 is thus regulated by a single common element of the deepfryer, namely the thermostat (or an equivalent member). Thecorresponding electrical connection thus implies that the resistorelements of the deep fryer and of the heater elements 11 are connectedin parallel.

[0043] By way of a variant, it is naturally possible to implement aconfiguration in which the system for regulating the temperature of thedeep fryer heater means is separate from the temperature regulationmeans 12 for regulating the temperature of the catalytic converter 10,said system and said means including respective temperature sensors. Inthis variant, since the reference temperatures are different for each ofthe thermostats, the effectiveness of the catalytic converter can beincreased.

[0044] In a particularly advantageous version of the invention, thecatalytic converter 10 is formed by a housing 15 which is mounted andintegrated in the lid 8 of the appliance.

[0045] The housing 15 contains a catalytic unit 16 forming the topportion of the housing 15, and extending in the vicinity of the outsideface of the cover 8. The housing 15 also contains the heater elements 11which extend in the vicinity of and under the catalytic unit 16 for thepurpose of heating it by radiation, without hot spots appearing. Thehousing 15 is provided with admission orifices 17 for admitting thecooking fumes to be treated, said orifices 17 being, for example,provided through a stainless steel bottom plate 18 of said housing 15that is situated substantially in register with the cooking bowl, theheater elements 11 being interposed between the orifices 17 and thecatalytic unit 16, and being disposed substantially in register withsaid orifices 17.

[0046] By means of this configuration, the cooking fumes to be treatedare heated in uniform and efficient manner, thereby guaranteeing thatthe catalytic converter operates properly and with good effectiveness.

[0047] Advantageously, the heater elements 11 are formed by a resistorin the form of a sinuous or helical coil, for example. In addition, itis particularly advantageous for the sinuous or helical resistor toextend over the entire surface of the catalytic unit 16 so as to obtain,by means of the sinuous configuration, a higher concentration of theelectrical resistor 11 at the periphery of the catalytic unit 16. Thisconfiguration considerably reduces the occurrence of hot spots in thecatalytic unit, in particular in the vicinity of its central portionwhich is free of change-of-direction zones corresponding to the zig-zagof sinuous coils.

[0048] Advantageously, and in order to obtain excellent effectiveness intreating the odors, the heater elements 11 have a maximum heat load ofnot more than 3 watts per square centimeter (W/cm²), and preferably lessthan or equal to 2.5 W/cm². This makes it possible to obtain a maximumtemperature of about 600° C. during treatment, which avoids overheatingand which makes it possible to maintain uniformity in treating thefumes.

[0049] As shown in particular in FIG. 3, the housing 15 isadvantageously mounted in the lid 8 of the appliance, which lid ismounted on a hinge A so that it can pivot between a closed position(FIG. 3) and an open position (not shown) in which the lid 8 issubstantially vertical.

[0050] According to an advantageous feature of the invention, the heaterelements 11 are connected to an electrical circuit including a switch20, such as a micro-switch associated with the position of the lid 8, sothat the switch 20 interrupts the electrical power supply to the heaterelements 11 as soon as the lid is opened or removed.

[0051] As shown in FIG. 3, the switch 20 is actuated by a rod 21 mountedto slide resiliently, longitudinally, and freely in a sleeve 22, sothat, in the rest position, the end 23 of the rod 21 comes flush withthe outside of said sleeve 22. In this free rest position, correspondingto the lid 8 being in the open position, the switch 20 opens theelectrical circuit of the heater elements 1. In contrast, while the lid8 is being closed, the end 23 of the rod 21 is engaged by the lid whenit reaches its substantially leaktight closure position, so that theelectrical circuit of the heater elements 11 is closed. Thisconfiguration guarantees good operating safety by ensuring that thecatalytic converter is switched off automatically whenever the lid isopened. This configuration also ensure the catalytic converter does notoperate whenever the user seeks to cook while taking action in the oil.When the lid is removed, since the springs urge the catalytic assemblyinto the vertical position, said catalytic converter does not operate,thereby avoiding any risk of burns.

[0052] The operating safety of the appliance may be increased by fittinga safety thermostat 25 in the appliance, in the vicinity of thecatalytic converter 10. Thus, the appliance of the invention may have anambient temperature and safety thermostat 25 connected to the electricalpower supply circuit of the heater elements 11, said thermostat 25 beingdisposed in the vicinity of the catalytic converter 10, e.g. in achamber that may be open or closed, and that is adjacent to thecatalytic converter 10, for the purpose of detecting the ambienttemperature around the catalytic converter 10 and of interrupting theelectrical power supply to the heater elements 11 in the event that thereference temperature is exceeded.

[0053] The ambient temperature thermostat 25 is particularly useful foravoiding problems of overheating of the plastics parts in the event thatventilation is temporarily insufficient, the thermostat 25 thenautomatically switching off the heater elements 11. During such atemporary interruption, the cooking fumes can exit without beingtreated, with the catalytic converter resuming normal operation as soonas the temperature detected by the safety thermostat 25 is lower thanthe reference temperature.

[0054] Advantageously, a backing plate 26 may be integrated under thehousing 15 and at some distance therefrom for providing a thermal brakeand for protecting the plastics structure of the lid 8 in the event oftemporary overheating.

[0055] Conventionally, the catalytic unit 16 may be made of a materialof the cordierite, ceramic, or zirconia-mullite type, with standardcalibrated holes of 100 cells per square inch (CPSI) or 400 CPSI, or itmay be made of a material of the 20 pounds per inch (PPI) foam type insupports, such as those sold by SICAT, for example.

[0056] The surface area of the catalytic unit 16 is computed so as toavoid head loss and so as to obtain an acceptable transit speed for thefumes. By way of example, the basic surface area of the catalytic unit16 may be 4000 square millimeters (mm²) for a height of at least about30 millimeters (mm), with calibrated holes of 200 CPSI or 400 CPSI. Inanother variant embodiment, the catalytic unit may have a basic surfacearea of about 8000 mm² with a reduced height of 12 mm for calibratedholes of 200 CPSI or 400 CPSI.

[0057] During cooking, the cooking fumes are directed towards the inletE of the catalytic converter 10 so as to penetrate into the orifices 17after being distributed along an inlet channel situated under and alongsaid admission orifices 17.

[0058] The cooking fumes are then preheated or heated by flowing overthe heater elements 11, they are then treated by catalysis by flowingthrough the catalytic unit or catalytic converter 16, and they are thendischarged to the outside of the deep fryer, preferably backwards viathe outlet S.

[0059] In addition to the odors being treated as they flow through thehot portions of the catalytic converter, the oil vapors contained in thefumes undergo pyrolysis which guarantees that the cooking fumes at theoutlet of the catalytic converter are treated in full.

[0060] The regulating system of the invention therefore makes itpossible to treat the cooking fumes and vapors particularly effectivelyby using a catalytic converter, while also implementing particularlysimple and effective temperature regulation means, and while complyingwith good safety conditions. The treated fumes as discharged are alsoinvisible.

Susceptibility of Industrial Application

[0061] An industrial application of the invention lies in designing andmanufacturing food-cooking appliances, and in particular deep fryers.

1/ An appliance for cooking food in a closed atmosphere, the appliancecomprising a bowl (6) and a lid (8), heater means for heating theappliance, for the purpose of performing the cooking, and a catalyticconverter (10) for treating the odors of the cooking fumes before thefumes are discharged to the outside, wherein: the catalytic converter(10) includes at least one heater element (11); and the appliancefurther comprises temperature regulation means (12) for regulating thetemperature of said heater elements (11), said temperature regulatingmeans (12) being organized to sense the temperature of the cooking zone.2/ The appliance according to claim 1, wherein the regulation means (12)further comprise a temperature sensor (12A) mounted in a manner such asto sense the temperature of the cooking bowl (6) as an image of thecooking temperature. 3/ The appliance according to claim 2, wherein thetemperature sensor (12A) is mounted against or on the outside wall ofthe bowl (6). 4/ The appliance according to claim 1, further comprisinga temperature regulation system for regulating the temperature of theheater means. 5/ The appliance according to claim 4, wherein the systemfor regulating the temperature of the heater means is associated withthe means (12) for regulating the temperature of the catalytic converter(10), said system for regulating the temperature of the heater meansincluding a temperature sensor that is common to said temperatureregulation means. 6/ The appliance according to claim 4, wherein thesystem for regulating the temperature of the heater means is separatefrom the means (12) for regulating the temperature of the catalyticconverter, said system for regulating the temperature of the heatermeans and said means for regulating the temperature of the catalyticconverter having respective temperature sensors. 7/ The applianceaccording to claim 6, wherein the sensor for sensing the temperature ofthe bowl is a thermostat. 8/ The appliance according to claim 7, whereinthe thermostat is placed against one of the group consisting of on thebottom of the bowl, and against and on the side wall of the bowl. 9/ Thecooking appliance according to claim 1, wherein the heater elements ofthe catalytic converter have a maximum heat load of not more than 3W/cm², and preferably less than or equal to 2.5 W/cm². 10/ The applianceaccording to claim 9, wherein the catalytic converter is formed by ahousing (15) containing a catalytic unit (16) and heater elements (11),said housing (15) being provided with admission orifices for admittingthe cooking fumes to be treated, the heater elements (11) beinginterposed between the orifices (17) and the catalytic unit (16), anddisposed substantially in register with said orifices (17). 11/ Theappliance according to claim 10, wherein the heater elements (11) areformed by a resistor in a sinuous configuration. 12/ The applianceaccording to claim 11, wherein the sinuous resistor (11) extends oversubstantially the entire surface of the catalytic unit (16). 13/ Theappliance according to claim 12, wherein the housing (15) is mounted inthe lid (8) of the appliance. 14/ The appliance according to claim 1,wherein the heater elements (11) are connected to an electrical circuitincluding a switch (20), such as a micro-switch, associated with theposition of the lid (8) so that the switch (20) interrupts theelectrical power to the heater elements (11) whenever the lid (8) isopened or removed. 15/ The appliance according to claim 1, furthercomprising a safety thermostat (25) connected to an electrical powersupply circuit of the heater elements (11), said thermostat beingdisposed in the vicinity of the catalytic converter for detecting theambient temperature and for interrupting the electrical power supply tothe heater elements (11) in the event that the reference temperature isexceeded. 16/ The appliance according to claim 1, wherein the appliancefurther comprises a deep fryer.